Ionosphere‐Thermosphere Variability Due To Tidal Forcing From Below Versus Solar and Magnetospheric Forcing From Above

Abstract The sub‐monthly longitude‐UT variability of the following ionosphere and thermosphere (IT) parameters: zonal (Un) and meridional (Vn) winds, temperatures (Tn), vertical plasma drifts () and electron densities (Ne) at 300 km due to tidal “forcing from below” () and solar flux and magnetosphere (SM) “forcing from above” during 2021 are quantified using a series of model simulations designed to separate these responses with respect to their origins. The external forcings are driven by tidal, solar wind, and solar flux observations. forcing includes DE3 to DW2 and SE3 to SW4 in the form of daily 45‐day running means. Ratios of ‐ to SM‐driven longitude‐UT variances () mostly range between roughly 0.2–1.5 for Un, 0.1–0.5 for Vn and 0.15–0.3 for within latitude, and reduce to smaller values at latitudes. for Ne range between 0.4 and 0.8 within latitude and reduce to 0.2–0.4 at latitudes. maxima within of 3.4, 0.7, 0.9, 1.0, 0.37 for Un, Vn, , Ne and Tn occur between day of year (DOY) 180 and 210, within the DOY 120–270 range where the major forcing occurs. Since the forcing excludes sub‐monthly meteorological variability of tides, the quoted represent lower limits. Secondary waves (SWs) due to tide‐tide‐nonlinear interactions comprise 10%–60% of the response, depending on IT parameter, DOY, and latitude, and serve to enhance its spatiotemporal complexity. The largest SWs are TE1, TW3, DW5, T0, TW1, and QW4.